It is generally agreed that conventional type hot blast stoves having external combustion chambers are costly to build and they require design compromises in order to solve problems of cyclical differential expansions of the lining, shells and hot blast mains.
Conventional hot blast stoves having internal combustion chambers have been developed to the extent that they are satisfactory for use at the temperatures commonly experienced in hot blast stoves. However, such stoves are not satisfactory for use at the very high blast temperatures, which are over 2200.degree.F., toward which blast furnace installations are moving as fast as the use of tuyere injectants and improved burdens permit. Such stoves though are inherently less costly initially for a given active heating surface than external combustion-chamber type stoves.
One factor which exerts the greatest limiting effect on the design of internal combustion chamber hot blast stoves for the desired very high hot blast temperatures, which are above 2200.degree.F., is the sensitive area at the burner level where great temperature differences exist in the refractories over the cross-sectional area. This is true even when ceramic burners are installed that fire in the upward direction along the vertical axis of the combustion chamber to avoid high intensity flame impingement on the vertical combustion chamber wall.
Heretofore, in order to minimize the serious consequences of the temperature differences at the burner cross-sectional level of internal combustion chamber stoves, slip joints, expansion joints, insulation layers, and heat resistant steel barriers have been proposed in the prior art. Also, silica brick has been used because of its refractory and thermal limits, even though it is sensitive to cooling below a temperature of 1100.degree.F.
An object of the present invention is to develop a hot blast stove that does not experience large temperature differences at horizontal cross sections like stoves of the prior art that does not necessitate the use of expansion joints, slip joints and barriers.